., Sukarno and Hendratta, Liany A. and Mangangka, Isri R. and Supit, Cindy Jeane and Ohmoto, Terunori
(2014)
EFFECTS OF REGULARLY SQUARE RIBS ROUGHNESS ON
TURBULENT FLOW STRUCTURE IN CASES TWO AND THREEDIMENSIONAL
ROUGHNESS IN AN OPEN CHANNEL.
In: The International Conference on Environmentally Friendly Civil Engineering Construction and Materials (EFCECM 2014), Manado - Indonesia, 13-14 November, Manado.
Abstract
Effects of regularly arrayed of square roughness on turbulent characteristics in an open
channel have been investigated with a completely rough bed surface with uniform stainless
square ribs, where the roughness heights, k = 10mm, longitudinal spacing, � = 4cm and
transverse spacing, � = 1cm. Detailed spatial measurements of streamwise and vertical
velocity fluctuations were conducted using Particle Image Velocimetry (PIV) in a vertical
plane along the completely rough bed surface.
Experimental results indicated that the maximum values of vertical and longitudinal
distribution of main flow velocity showed that two-dimensional roughness is greater than
three-dimensional roughness, also showed that the maximum values of Reynold shrear
stress two-dimensional roughness have occurred at the front of the roughness elements,
however the maximum values of Reynold shrear stress in case of three-dimensional
roughness have occurred at the behind of the roughness elements, it was evident that twodimensional
roughness has two-directions of flow velocity i.e. on the x-axis and w-axis
directions and three-dimensional roughness has three-direction of flow velocity on the xaxis,
w-axis and v-axis directions, respectively.
It was described that three-dimensional roughness has barrier to flow bigger than twodimensional
roughness elements, although distribution of horizontal velocity, v-direction of
this experiments yet explained.
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